Sixty-eight per cent of S&P 500 companies to report earnings so far have bested expectations, said S&P Global Market Intelligence.

"The majority of earnings reports are better than expected," said Michael James, managing director of equity trading at Wedbush Securities.

"Certainly there are some disappointments, but for the most part, they are better than estimates."

Ford plunged 8.1 per cent as it warned it may miss its 2016 profit targets due in part to a cooling of the US auto boom that has forced car dealerships to boost incentives.

Rival automakers General Motors and Fiat Chrysler lost 3.2 per cent and 4.8 per cent, respectively.

Whole Foods Market tumbled 9.3 per cent as it reported a 22.1 per cent drop in fiscal third-quarter net income to US$120 million and said comparable store sales dropped 2.6 per cent.

Other companies to rally after earnings reports were Groupon, up 28.8 per cent; GrubHub, up 24.4 per cent; and Tempur Sealy International, up 16.8 per cent, Cloud-computing company NetSuite surged 18.4 per cent on news it agreed to be acquired by software giant Oracle for US$9.3 billion. Oracle rose 0.6 per cent.